The aim of this study was to verify the hypothesis that Lenné – a well-known landscape architect of the nineteenth century – was the designer of the landscape park at Owińska. The study is based on written sources and cartographic materials depicting Owińska. The composition of the garden establishment has been analysed and the results have been compared with Lenné’s planning workshop. Although there is no direct evidence of Lenné’s involvement in the park design at Owińska, the garden composition bears some similarities to other garden compositions designed by Lenné. Surviving cartographic documents showed that the landscape structure, generally attributed to this author, was realised in the second half of the nineteenth century, probably after the death of Lenné.